1. Field of the Invention
The present invention relates to an apparatus for processing embroidery data to control a sewing machine to form an embroidery on a work sheet.
2. Related Art Statement
There is known an embroidery sewing machine which automatically forms an embroidery on a work sheet such as a work cloth. Embroidery data are used to control the sewing machine to automatically form the embroidery on the work sheet. The embroidery data may include sets of stitch-position data representing stitch positions located on the outline of an outline-bounded area to be filled with stitches to provide the embroidery. In this case, each stitch position may be defined by respective amounts of movement of the work sheet relative to the sewing needle in the X and Y directions pre-determined for the sewing machine. Otherwise, the embroidery data may include sets of block data representing respective outlines of polygonal blocks as divided parts of an outline-bounded area, and stitch-density data representing a stitch density, e.g., number of stitches to be formed in each polygonal block. U.S. Pat. No. 5,189,623 assigned to the Assignee of the present application discloses an embroidery data processing apparatus which automatically produces such embroidery data.
U.S. patent application Ser. No. 08/254,790 assigned to the Assignee of the present application discloses another embroidery data processing apparatus which may be constituted by a personal computer (PC) and an image scanner connected to the PC. The disclosed apparatus processes embroidery data based on an original image in the following manner:
First, the image scanner is operated to read in or pick up an original image from an original (e.g., color image painted or printed on a white base sheet), so that the PC produces image data representing the original image. Next, the PC divides, based on the image data, the original image into one or more outline-bounded areas each of which is independent of the other areas. For example, regarding cherries, A, shown in FIG. 4, the disclosed apparatus divides the original image A into three outline-bounded areas, i.e., stem, B, in, e.g., blue color, first cherry, C, in, e.g., yellow color, and second cherry, D, in, e.g., red color, as shown in FIGS. 5(a), 5(b), and 5(c), respectively. Then, the PC produces sets of outline data representing respective outlines of the embroidery areas B, C, D, according to a known outline determining algorithm, and finally produces embroidery data based on the thus obtained outline data. The PC may produce, as the embroidery data, sets of block data representing the respective outlines of polygonal blocks such as quadrangles and/or triangles, e.g., X and Y coordinates of the positions of the vertices of the quadrangular or triangular blocks. Alternatively, the PC may produce, as the embroidery data, sets of stitch-position data representing stitch positions located on the outline of each of the polygonal blocks where, e.g., satin stitches or seed stitches are formed to fill the inside area of each block.
Meanwhile, there are known various stitching manners that may be employed to fill an embroidery area, i.e., produce an embroider in the embroidery area; for example, satin stitching shown in FIG. 7(a), seed stitching shown in FIG. 7(b), and zigzag stitching shown in FIG. 7(c). The satin stitching is characterized by connecting the two opposed portions of an outline, R, of an embroidery area, with a "single" stitch, s1, i.e., without any needle's penetration of the work sheet inside the outline R. The stitch density for the satin stitching may be defined by a number of the single stitches s1 to be formed in unit length in an embroidering direction indicated at arrow in FIG. 7(a). The embroidering direction may be parallel to a straight line connecting a stitch-start position, S, and a stitch-end position, E, on the outline R. The start and end positions S, E may be determined as the two positions that are the most distant from each other on the outline R.
The seed stitching is characterized by connecting the two opposed portions of an outline, R, of an embroidery area, with a series of "unit" stitches, s2, i.e., with needle's penetrations of the work sheet at regular intervals of distances inside the outline R. The stitch density for the seed stitching may be defined by a number of "stitch lines" to be formed in unit length in an embroidering direction indicated at arrow in FIG. 7(b). Each stitch line consists of a series of unit stitches s2 connecting the two opposed portions of the outline R. The embroidering direction, and start and end positions S, E, for the seed stitching may be determined in the same manners as those for the satin stitching.
The zigzag stitching is characterized by forming, along a reference line, a number of stitches, s3, having a constant width. The stitch density for the zigzag stitching may be defined by a number of the stitches to be formed in unit length along the reference line.
In the event that two identical embroidery areas are embroidered by two different stitching manners, respectively, the two embroideries produced may give different impressions regarding the quality of conformance or finishing. Therefore, it is necessary for a user to specify a stitching manner suitable for each embroidery area. However, in the prior apparatus, only a single sort of stitching manner is employed to embroider all embroidery areas. Otherwise, in a different prior apparatus, a user is required to select one of different stitching manners to embroider each of various embroidery areas.
However, in the case where only the satin stitching, for example, is used to embroider various embroidery areas having different shapes, this manner may not be suitable for elongate embroidery areas for which the zigzag stitching is more suitable, and not suitable for large areas for which the seed stitching is more suitable. In addition, in the case where a user is required to select one of different stitching manners for embroidering each of various embroidery areas, it is cumbersome and time-consuming to accomplish the task, increasing the burden on the user. In the last case, the user may not be able to select a suitable stitching manner for each embroidery area so long as he or she is not familiar with the task.